Method and materials for making a monolithic porous pad cast onto a rotatable base

ABSTRACT

The present invention includes methods and materials for cleaning materials, particles, or chemicals from a substrate with a brush or pad. The method comprising: engaging a surface of a rotating wafer with an outer circumferential surface of a rotating cylindrical foam roller, the cylindrical foam roller having a plurality of circumferentially and outwardly extending spaced apart nodules extending from the outer surface, each nodule defining a height extending from the outer surface of the cylindrical foam roller to a substrate engagement surface of the nodule, the substrate engagement surface of one or more of the nodules having a rounded configuration; and positioning the cylindrical foam roller on the substrate such that the one or more nodules are positioned to have only the rounded substrate engagement surface contact the substrate such that no linear surface of the one or more nodules contacts the substrate.

CROSS REFERENCES TO RELATED APPLICATIONS

This patent application is a divisional of U.S. patent application Ser.No. 13/190,191, filed Jul. 25, 2011, now U.S. Pat. No. 8,533,895, whichclaims the benefit of U.S. patent application Ser. No. 10/566,847, filedJul. 13, 2004, issuing Jul. 26, 2011 as U.S. Pat. No. 7,984,526, whichclaims the benefit of, U.S. Provisional Patent Application Ser. No.60/493,992 which was filed on Aug. 8, 2003, titled METHODS FOR REMOVINGMATERIALS FROM A SUBSTRATE USING A MONOLITHIC POROUS PAD CAST ON AROTATABLE BASE invented by Briant Enoch Benson; this patent applicationalso claims the benefit of, U.S. Provisional Patent Application Ser. No.60/493,755 which was filed on Aug. 8, 2003, titled METHODS AND MATERIALSFOR MAKING A MONOLITHIC POROUS PAD FORMED ONTO A ROTATABLE BASE inventedby Briant Enoch Benson; this patent application also claims the benefitof U.S. Provisional Patent Application Ser. No. 60/493,993 which wasfiled on Aug. 8, 2003, titled DEVICE FOR REMOVING MATERIAL FROM ASUBSTRATE HAVING INTERCHANGEABLE FLUID AND MOUNTING FITTINGS invented byBriant Enoch Benson; this patent application also claims the benefit ofU.S. Provisional Patent Application Ser. No. 60/557,298 which was filedon Mar. 29, 2004, titled A MONOLITHIC POROUS PAD FORMED ONTO A ROTATABLEBASE invented by Briant Enoch Benson. All of the above identified patentapplications and patents are incorporated herein by reference in theirentireties.

BACKGROUND

In the fabrication of semiconductor devices, there is a need to performchemical mechanical polishing (CMP) operations and wafer cleaning.Typically, integrated circuit devices are in the form of multi-levelstructures. At the wafer level, transistor devices having diffusionregions are formed. In subsequent levels, metal interconnect lines arepatterned and electrically connected to the transistor devices to definethe desired functional device. As is well known, patterned conductivelayers are insulated from other conductive layers by dielectricmaterials, such as silicon dioxide. As more metallization levels andassociated dielectric layers are formed, the need to planarize thedielectric material grows. Without planarization, fabrication of furtherinterconnect and dielectric layers becomes substantially more difficultdue to the higher variations in the surface topography. In semiconductormanufacturing processes, metal interconnect patterns are formed in adielectric material on a wafer, and then, chemical mechanicalplanarization, CMP, operations are performed to remove the excess metal.After any such CMP operation, it is necessary that the planarized waferbe cleaned to remove particulates and contaminants.

In the manufacture of electronic devices such as integrated circuits,the presence of particulate contamination, trace metals, and mobile ionson a wafer is a serious problem. Particulate contamination can cause awide variety of problems such as localized corrosion, scratching, and“shorts” in the integrated circuit. Mobile ion and trace metalcontaminants can also lead to reliability and functional problems in theintegrated circuit. The combination of these factors results in lowerdevice yields on a wafer, thereby increasing the cost of an averagefunctional device on the wafer. Each wafer, being at different stages offabrication, represents a significant investment in terms of rawmaterials, equipment fabrication time, and associated research anddevelopment.

Chemical-mechanical polishing (“CMP”) is a commonly used technique forplanarizing a film on the wafer prior to subsequent processing of thewafer. CMP usually involves the introduction of a polishing slurryhaving 50-100 nanometer sized abrasive particles onto the surface of apolishing pad. The wafer with the layer of material, dielectric ormetal, to be removed is placed against the surface of a polishing padwith a slurry. Rotating the wafer against the rotating polishing paddecrease the thickness of the layer through a combination of chemicaland mechanical actions. The slurries typically are water based and caninclude fine abrasive particles such as silica, alumina, and other metaloxide abrasive materials. After polishing is complete, the processedwafers must be cleaned to completely remove residual slurry and otherresidue from the polishing process. The surface is the ready for otherprocessing steps such as electrochemical deposition, etching, andphotolithography.

To clean residual slurry material from the surface of the polishedsurface, especially particles less than 0.1 microns in diameter,cleaning brushes are commonly used. These cleaning brushes are usuallycylindrical in shape and are rotated along a center axis of the brush.The cleaning brushes are also often made of a foam or porous polymericmaterial such as polyvinyl alcohol (“PVA”). The combination ofrotational movement of the brush and force or pressure placed on thebrush against the wafer as well as the application of cleaning fluids ordeionized water causes residual slurry materials to be removed from thesurface of the wafer.

These brushes have protrusion or nodes on their surface for contact andmaterial removal from a substrate. Brushes are formed as sleeves and areslid over a core support which is used to deliver fluids to the brushand to rotate the brush. After extended use, the brush is replaced witha new brush sleeve and requires the polishing tool be stopped adding tolost productivity and downtime. Alignment of the brush protrusions alongthe brush core is important for consistent contact of the brush with thesubstrate. Asymmetric alignment and distortion of the spacing of thenodes on the sleeve is a problem with sleeve replacement. Newlyinstalled brushes must be broken in, flushed, and gapped prior tocleaning product substrates. Often time dummy wafers are used to ensurethe cleanliness, and operational stability including dimensional,rotational and contact of the brush with the dummy wafers. Thisnon-value added step is costly for manufactures in time and dummywafers.

To perform the cleaning operations in an automated manner, fabricationlabs employ cleaning systems. The cleaning systems typically include oneor more brush boxes in which wafers are scrubbed. Each brush boxincludes a pair of brushes, such that each brush scrubs a respectiveside of a wafer. To enhance the cleaning ability of such brush boxes, itis common practice to deliver cleaning fluids through the brush (TTB).TTB fluid delivery is accomplished by implementing brush cores that havea plurality of holes that allow fluids being fed into the brush core ata particular pressure to be released onto the substrate surface. Thefluid is distributed from the brush core through the polymeric materialand onto the substrate surface. Ideally, the chemicals flow through thebore and then flow out of the core at an equal rate from all of thebrush core holes. It has been found that the chemicals delivered to thecore are not flowing out of all of the holes at the same orsubstantially the same rate and that brush core holes near the chemicalreceiving end usually flow out chemicals at a substantially faster ratethan holes at the opposite side of the chemical receiving end.

As semiconductor feature sizes decrease and device performancerequirements continue increase, cleaning engineers are also challengedto improve their associated processes. To meet these demands, the samecleaning equipment is now being used to perform operations other thanbasic de-ionized (DI) water cleaning. Such operations include theapplication of sophisticated chemicals to remove particulates and/or toetch precise films of materials from the surfaces of a wafer. Manycleaning systems are now required to also apply reactive chemicals, suchas hydrofluoric acid, uneven application will have a severe impact onthe wafer being processed. For instance, if more HF is applied to onepart of the wafer and less is applied to another part of the wafer, thesurface of the processed wafer may exhibit variations in the amount offilm removed across the wafer.

SUMMARY

Embodiments of the present invention include methods and materials formaking a porous brush or pad that is cast or molded directly onto arotatable base used to support the pad. The brush or pad can be used forcoating at least a portion of a substrate with a fluid or it can be usedfor removing materials, particles, or chemicals from a substrate. Thebrush or pad includes a rotatable base or core that interlocks with aporous pad material. The base includes an inner surface and an outersurface and can have a plurality of channels in the base forinterlocking the porous pad material with the base. The porous padmaterial covers at least a portion of the outer surface of the base andmay be used for removing material from various substrates. The porouspad material has a monolithic structure and can fill one or more of thechannels in the base thereby interlocking the porous pad material withthe base. Preferably the channels filled with the porous pad materialfluidly connect the inner surface with the outer surface of the base.

One embodiment of the present invention is a device for removingmaterial from a substrate that includes a rotatable base supporting aporous pad material. The base includes an inner surface and an outersurface and has channels for distributing a fluid to the porous padmaterial from the inner surface of said base to the outer surface of thebase. The porous pad material covers at least a portion of the outersurface of the base and with the fluid is used for removing materialslike particle and thin films from substrates. Preferably the porous padmaterial interlocks with the channels of the base and more preferably itfluidly connects the inner and outer surfaces of said base. Therotatable base can have one or more fittings mated with it thatinterconnect the rotatable base with a source of fluid and a spindle orother fixture for rotating the base. The fittings, which may includefluid fittings and machine drive fittings are mated to the base bybonding. By using different fittings a single rotatable base may beadaptable to different material removal tools by using different sizedor shaped fittings with the base.

Another embodiment the present invention is a device for removingmaterial from a substrate that includes a rotatable base supporting aporous pad material having protrusions or nodes on its surface. Therotatable base includes an inner surface and an outer surface and haschannels for distributing a fluid to a substrate through the protrusionbearing porous pad material. The fluid flows from the inner surface ofthe base to the outer surface of the base. The porous pad materialcovers at least a portion of the outer surface of the base, and with thefluid, can be used for removing materials like particle and thin filmsfrom substrates. The rotatable base has one or more fittings mated withit which interconnect the rotatable base with a source of fluid and aspindle or other fixture for rotating the base. Preferably the porouspad material interlocks with the channels of the base and morepreferably it fluidly connects the inner and outer surfaces of the base.The fittings, which may include fluid fittings and machine drivefittings can be mated to the base by bonding. By using differentfittings, a single rotatable base may be adaptable to different materialcoating and removal tools by using different sized or shaped fittingswith the base. The rotatable base may be a brush for scrubbingsemiconductor wafers.

Embodiments of the present invention are directed to methods of cleaningsubstrates by contacting them with a rotating porous pad material castor molded onto a rotatable base core. The pad covering the rotatablebase includes an inner surface and an outer surface and a plurality ofchannels in the base for interlocking the porous pad material with thebase. The porous pad material covering at least a portion of the outersurface of the base can be used for removing material from a variety ofsubstrates. In the process a material removal or cleaning fluid isdeposited onto a surface of the substrate through the brush. Throughrotation of the brush and action of the fluid, material can be removedfrom the substrate surface by rotating the porous pad material againstthe substrate. Preferably the channels in the base are filled with theporous pad material to interlock the porous pad with the base andfluidly interconnect the inner surface with the outer surface of thebase to distribute the fluid to the pad surface. The method may furtherincluding the act of flushing a fluid through the porous pad cast ontothe rotatable core to remove substrate material adhering to the porouspad and its protrusions or nodes. One or more surfaces of the substratemay have material removed from them by contacting each with a rotatingporous pad molded onto a rotatable base along with a fluid.

Preferably the porous pad material molded onto the base includesprotrusions like bristles or nodes or it may have surface recesses likegrooves. Preferably the porous pad material covers the inner surface ofthe rotatable base core. The channels of the base preferably fluidlyconnect the inner surface of the core with the outer surface of the coreand one or more of the channels are filled with the porous pad materialwhich interlocks the base with the porous pad material and maintains thealignment of nodes on the porous pad during rotations. Fluid may bedeposited onto the substrate through the core of the rotatable base byflowing fluid through the porous pad filled channels and out to thesubstrate surface.

Materials removed from the substrate by embodiment of the presentinvention may include thin film metal oxide films, silica films,semiconductor oxide films, particles of various composition, or chemicalresidues. Preferably the substrate is a wafer which includes copper orcopper interconnects. Brushes of the present invention may be used toclean memory media and wafers regardless of texture or type sputteredmetal on the wafer.

In another embodiment, the brush or pad includes a rotatable base forsupporting a porous pad material cast or molded onto the base. The baseincludes an inner surface and an outer surface and has a plurality ofchannels fluidly interlocking the porous pad material with the base. Theporous pad material covering at least a portion of the outer surface ofthe base and has surface protrusions or recesses. The porous padmaterial having the surface protrusions preferably fills one or more ofthrough channels in the base to distribute fluid from the inner surfaceof the base to the outer surface of the base through the porous padmaterial. Preferably the porous pad material interlocking with thechannels and covering the outer surface of the base forms a monolithicstructure.

In another embodiment, the brush or pad includes a rotatable base forsupporting a porous pad material cast or molded onto the base. The baseincludes an inner surface and an outer surface and a plurality ofchannels in the base for interlocking the porous pad material with thebase. Preferably the channels fluidly connect the inner surface with theouter surface of the base. To aid in the distribution of fluid from theinner surface of the base to the porous pad covering the outer surfaceof the base, through channels may be positioned throughout the base froma center point of the base to an outer edge of the base that may beinterconnected by surface channels. The porous pad material covers atleast a portion of the outer surface of the base and the porous padmaterial fills one or more of the through channels and or surfacechannels in the base to distribute fluid from the inner surface of thebase to the outer surface of the base through the porous pad material.Preferably the porous pad material in the through channels and coveringthe outer surface of the base form a monolithic structure.

One embodiment of the present invention is an article having a rotatablebase with an adherent porous pad material covering at least a portion,and preferably all of the rotatable base surface including through holesin the base. The adherent porous pad material covering the rotatablebase may include a first porous pad material covering at least aportion, and preferably all of the rotatable base surface that adheresto the rotatable base and permits fluid flow through the base and porouspad. The adherent porous pad material on the base may have a secondadherent layer of porous pad material molded or cast onto the firstadherent layer. Optionally one or more through holes in the base mayalso be filed with a the porous pad material. The adherent porous padmaterial a covering at least a portion of the outer base surfacemaintains its porosity after bonding to the base surface and permitsfluid flow from the core of the rotatable base through holes or channelsin the base to the outer porous pad surface layer which may be used forapplying fluid to a substrate, removing films from a substrate, orcleaning a substrate.

In another embodiment of the present invention, the porous pad materialis deposited by casting or molding into recessed channels or throughholes in the base. The channels and through holes in the housing baseinterlock with the porous pad material and prevent lifting of the porouspad material from the base surface during use. The channels may have anoptional adherent porous first layer onto which a second porous layer iscast. The interlocking of the porous pad material with the base alsoaids in maintaining the height and the position of the protrusions ornodes of the porous pad material along the base surface or its axis andprovides more uniform contact of the nodes with the substrate surface.The interlocking of the porous pad material and the housing base alsoeliminates or substantially reduces the twisting of brush rollers thatcommonly occurs with brushes sleeves which are slipped onto a basehousing or which are placed on two part base housings. The twisting ofsleeve type brushes and rollers may lead to non-uniform andirreproducible substrate surface fluid contact, uneven material removalor cleaning as well as accelerated brush wear. Monolithically formedporous pad material interlocked with the rotatable base maintains nodealignment straight, eliminates or reduces ripping of nodes duringmounting, and permits much higher tolerance on node size and shapegiving more uniform contact with the substrate to be treated. Preferablythe channels filled with the porous pad material fluidly connect theinner and outer surfaces of the base.

Embodiments of the present invention include methods and materials formaking a brush or pad that is cast or molded directly onto the core usedto support the pad. The pad or brush can be used for removing materials,particles, or chemicals from a substrate. The brush or pad includes arotatable base or core for supporting a porous pad material. The baseinclude an inner surface and an outer surface and a plurality ofchannels in the base for interlocking the porous pad material with thebase. The porous pad material covers at least a portion of the outersurface of the base and is used for removing material from varioussubstrates. The porous pad material has a monolithic structure and fillsone or more of the channels in the base and interlocks the porous padmaterial with the base. Preferably the channels fluidly connect theinner surface with the outer surface of the base.

The channels in the base to which the porous pad material is interlockedby casting or molding maintains the alignment of the porous pad materialon the rotating base, more preferably the casting or molding of the padmaintains the integrity, alignment, and spatial distribution or nodulesof the porous pad material on the rotating base. Channels whichinterconnect the inner and outer surfaces also aid in the distributionof fluid from the inner surface of the base to the outer surface of thebase having the porous pad material in contact with the substrate.Preferably the porous pad material in the channels, the inner basesurface, and that covering the outer surface of the base are monolithicin structure. The substrate can be any substrate that may need toundergo a scrubbing to complete a cleaning operation or a substrate thatis planarized by an etching operation, or other preparation. Forinstance, the substrate can be a semiconductor wafer, a disk, opticallenses, a flat panel display. Preferably the substrate will benefit froma brush or pad that can deliver substantially uniform and controlledamounts of fluid to the substrate. Even more preferably the substratewill benefit from surface material removal or cleaning with a brush orpad that can deliver substantially uniform and controlled amounts offluid to the substrate and maintain consistent and uniform contact ofthe protrusions on the pad with the substrate.

In another embodiment, a method is provided for making the brush or padsuch that the porous pad material covering the base and the porous foammaterial filling the through channels of the base are monolithic.Preferably the method includes forming a monolithic porous pad materialon the outside of the base which also interlocks with channels on thebase. The method includes pouring a combination of un-polymerized porousbase monomer and a catalyst into a mold including the base, filling oneor more channels in the base, and then curing the combination to formthe article. The article is released from the mold. In anotherembodiment, a method is provided for making the brush or pad such thatthe porous pad material covering the base and the porous foam materialfilling the through channels of the base are monolithic. Preferably themethod includes forming a monolithic porous pad material on the outsideof the base which also interlocks with channels of the base. The methodincludes pouring a combination of un-polymerized porous base monomer anda catalyst into a mold including the base, filling one or more channelsin the base, and then curing the combination to form the article. Thearticle is released from mold. Preferably the mold is treated with arelease agent to aid in the release of the monolithic porous padstructure.

Embodiments of the present invention may be used to apply coatings tosubstrates or as brushes for removing particles, thin film, or chemicalresidues from a wide variety of substrates such as but not limited tosemiconductor wafers, flat panel displays, hard disks, and opticaldevices such as lenses. Advantageously embodiments of the presentinvention permit great flexibility in the manufacturing and assembly ofsuch brushes. This is because a single base with a porous pad can beused on an number of tools. In the present invention, brushes may bemounted on a variety of cleaning tools by simply changing the one ormore fittings that are to be connected to the rotatable base so that therotatable base and pad can perform their function of cleaning orremoving material from the one or more surfaces of the substrates.

Advantageously, embodiments of the present invention may be used toprovide a fluid to the surface of a substrate for a cleaning or materialremoval operation such as a chemical mechanical planarization or postCMP scrubbing processes. By interlocking the porous pad material withthe base, the porous pad material in held in place relative to the base.Node misalignment and twisting in embodiments of the present inventionsubstantially reduces or eliminated brush walking and twisting comparedto slip on sleeve style brushes. An additional advantage of the presentinvention is that it may be used to distribute fluid to both roller andpad type base fixtures. The porous pad material in the channels may alsobe used to control the liquid flow from the fluid source to thesubstrate. This allows the number of perforations or through channels inthe housing core to be decreased and their size or surface areaincreased without significantly increasing the overall amount of liquidused. This is particularly advantageous since larger perforations orthrough channels in the housing reduces localized nonuniform flushing ofthe porous pad. Further, by restricting the flow of liquid, the porouspad causes a uniform pressure buildup inside of the distributor. This inturn can be used to form through holes that ensure that both ends of thebrush receive the same amount of liquid and are uniformly flushed whichimproves particulate removal from the brush and reduces or eliminatesuneven wear of the brush.

An advantage of a brush cast onto a disposable core is that the core andbrush are joined together eliminating the slippage, expansion, and lossof concentricity observed with brushes friction fit onto a core. Thebrush cast onto the core eliminates the need for special mounting standand time associated with mounting friction brush sleeves onto cores.

DESCRIPTION OF THE DRAWINGS

In part, other aspects, features, benefits and advantages of theembodiments of the present invention will be apparent with regard to thefollowing description, appended claims and accompanying drawings where:

FIG. 1A illustrates a cross section along the length of a hollowcylindrical tube with through channels useful for a rotatable base in anembodiment of the present invention; FIG. 1B is an illustration of thehollow cylindrical tube with one or more through channels filled with aporous pad material; FIG. 1C illustrates a rotatable base with filledthrough channels including fluid fittings and tool mounting fitting;

FIG. 2 is a schematic illustration of a cross section along the lengthof a hollow cylindrical housing base in an embodiment of the presentinvention with through channels and the outer surface of the baseincluding a porous pad material with optional protrusions on the padsurface;

FIG. 3A is a schematic illustration of a cross section along the lengthof a hollow cylindrical housing base in an embodiment of the presentinvention with through channels, the inner surface, and the outersurface of the base including a filling or covering of a porous padmaterial without fluid fitting or a fitting for connection of the baseto a cleaning tool; FIG. 3B is a schematic illustration of a crosssection along the length of a hollow cylindrical housing base in anembodiment of the present invention with through channels, the innersurface, and the outer surface of the base including a filling orcovering of a porous pad material with fluid fitting and a fitting forconnection of the base to a cleaning tool;

FIG. 4 is a schematic diagram of a hollow cylindrical tube useful in asa base or core for embodiments of the present invention illustratingdifferent through channels filled with a porous pad material;

FIG. 5A is a schematic diagram of a rotatable base in the form of a diskshape housing in an embodiment of the present invention with an adherentporous pad layer covering the rotatable base and a second adherentporous pad material molded or cast onto the first adherent porous padlayer; FIG. 5B is a schematic illustration of a cross section along thediameter of a disk shaped housing base in an embodiment of the presentinvention with through channels, the inner surface and the outer surfaceof the rotatable base including a filling or covering of a porous padmaterial;

FIG. 6 is a schematic diagram of a cross section along the diameter of arotatable hollow tube housing base in an embodiment of the presentinvention with hollow through channels filled with a porous material andouter surface of the base covered with a porous pad material havingprotrusions.

FIG. 7 is a schematic diagram of a cross section along the diameter of arotatable hollow tube housing base in an embodiment of the presentinvention with hollow through channels filled with a porous material,the inner surface of the base covered with a porous pad material and theouter surface of the base covered with a porous pad material includingprotrusions;

FIG. 8A is a schematic diagram of a rotatable hollow tube housing basein an embodiment of the present invention with an adherent porous padlayer covering the base and a second porous pad material adhering to thefirst porous pad layer that has been molded or cast onto the adherentfirst porous layer; FIG. 8B is a schematic diagram of a cross sectionalong the diameter of a hollow tube housing base in an embodiment of thepresent invention with a rotatable hollow cylinder with through channelsfilled with a first porous pad material, the outer surface of the basecovered with a first porous pad material and a second porous padmaterial including protrusions covering the first porous pad material;

FIG. 9 is a schematic diagram of an embodiment of the present inventioncleaning one or more surfaces of a substrate;

FIG. 10A illustrates a cross section of a brush pad with protrusions;FIG. 10B illustrates a cross section along the diameter of a hollow tubehousing base in an embodiment of the present invention with hollowthrough channels filled with a porous material and the outer surface ofthe base covered with a first porous pad material. FIG. 10C illustratesa brush formed by combining the components in FIG. 10A and FIG. 10B;

FIG. 11A illustrates a cross section of a brush pad with protrusions;FIG. 11B illustrates a cross section along the diameter of a hollow tubehousing base in an embodiment of the present invention with hollowthrough channels filled with a porous material; FIG. 11C illustrates abrush formed by combining the components in FIG. 11A and FIG. 11B;

FIG. 12 illustrates a cross section of a housing base tube havingchannel grooves in a rotatable base surface for interlocking with theporous base material and retaining the alignment and position of nodeson the surface of a porous pad material covering the base surface;

FIG. 13 shows a photograph of cross section of a brush molded onto arotatable base using methods and materials of the present invention;

FIG. 14 is a diagram of a mold that can be used to make a brush moldedonto a rotatable base of the present invention;

FIG. 15A is a non limiting illustration of an embodiment of the presentinvention having a porous pad material cast onto an adherent firstporous material on a rotatable substrate having through holes; FIG. 15Bis a non-limiting illustration of an embodiment of the present inventionof a porous pad material cast onto an adherent first porous material ona rotatable nonporous substrate;

FIG. 16 is an illustration of a material removal pad of the presentinvention including a porous pad molded into channels of a rotatablecore and having interchangeable fluid and tool drive mounting fitting onthe core;

FIG. 17 is an illustration of a rotatable base core of the presentinvention having interchangeable fluid and mounting fitting on the core;

FIG. 18 is an illustration of a cross section of a material removal padof the present invention including a porous pad molded into channels ofa rotatable core;

FIG. 19A is an illustration of an unassembled rotatable base core withinterchangeable fluid and tool mounting fitting; FIG. 19B is anillustration of the fluid fitting and tool mounting fitting insertedinto the base core; FIG. 19C is a detail (A) of the joint formed betweenthe base core and the fluid fitting;

FIG. 20 is an illustration of a fluid fitting 1910 of FIG. 19A indetail;

FIG. 21A is an illustration of the outside of a core (1920) of the FIG.19A; FIG. 21B is a view of a cross section of the core (1920) of FIG.19A;

FIG. 22 is a cross section of core in FIG. 19A along a rotational axisof the core illustrating placement of channels and through holes in therotatable core;

FIG. 23 is an illustration of a tool mounting fitting (1930) of FIG.19A;

FIG. 24 is a illustration of another embodiment of an unassembled corewith interchangeable fluid and tool mounting fittings;

FIG. 25 is a detailed illustration the fluid fitting of FIG. 24;

FIG. 26 is a detail illustration of the tool mounting fitting of FIG.24.

DETAILED DESCRIPTION

Before the present compositions and methods are described, it is to beunderstood that this invention is not limited to the particularmolecules, compositions, methodologies or protocols described, as thesemay vary. It is also to be understood that the terminology used in thedescription is for the purpose of describing the particular versions orembodiments only, and is not intended to limit the scope of the presentinvention which will be limited only by the appended claims.

It must also be noted that as used herein and in the appended claims,the singular forms “a”, “an”, and “the” include plural reference unlessthe context clearly dictates otherwise. Thus, for example, reference toa “channel” is a reference to one or more channels and equivalentsthereof known to those skilled in the art, and so forth. Unless definedotherwise, all technical and scientific terms used herein have the samemeanings as commonly understood by one of ordinary skill in the art.Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of embodimentsof the present invention, the preferred methods, devices, and materialsare now described. All publications mentioned herein are incorporated byreference. Nothing herein is to be construed as an admission that theinvention is not entitled to antedate such disclosure by virtue of priorinvention.

Although the present invention is described in conjunction with thescrubbing of a semiconductor substrate or wafer, it will be appreciatedthat other substrates may be processed or coated by the methods andapparatuses of the present invention. Further, it will be appreciatedthat reference to a semiconductor substrate or wafer may include a bareor pure semiconductor substrate, with or without doping, a semiconductorsubstrate with epitaxial layers, a semiconductor substrate incorporatingone or more device layers at any stage of processing, substratesincluding copper or copper alloy interconnects, other types ofsubstrates incorporating one or more semiconductor layers such assubstrates having semiconductor on insulator (SIO) devices, orsubstrates for processing other apparatuses and devices such as flatpanel displays, MEMS devices, multichip modules, etc.

It will be clear to one of ordinary skill in the art that some of thesteps in the cleaning system described herein may occur in another orderand/or with various solutions depending upon the substrate or substratelayer being cleaned. For example, different cleaning solutions, such aswater, water and isopropyl alcohol, citric acid, ammonium hydroxide,ammonium citrate, and hydrofluoric acid solution (or mixtures ofsolutions) may be used in one of the brush stations. Also, other systemsmay include one brush station, or two or more than two brush stations.Moreover, other systems may omit one or more of the above stations/stepsand may include additional processing stations, such as a CMP station.

Sponges or brushes in the form of replaceable sleeves have problems withwalking and twisting on their brush cores and have shorter brush life.Rotation rates for brushes generally range from about 800 to 1500 rpmwith from about 0.8 to 2 pounds of drag. Higher rotation rates and dragare often preferred to clean an article at a faster rate, however thismay lead to rapid degradation of nodes on the brush or pad. Cast on thecore brushes described in embodiments of the present invention can berotated at greater radial velocities because they cannot walk or twistdue to interlocking of the base core with the porous pad material.Walking refers to stress induced migration of the brush to a differentlocation on the core. Twisting refers to stress induced relocation ofnodules out their original alignment.

Cleaning and material removal solutions which may be used with themethod of the present invention include but are not limited to deionizedwater and mixture of chemicals in deionized water. The chemicals mayinclude fluoride compound such as HF or NH.sub.4F; NH.sub.4OH, anorganic acid, an ammonium salt of an organic acid, alcohols, an anionicsurfactant; a basic, a neutral, or an acidic pH environment. For examplehydrochloric acid (HCl) may be added to the solution to adjust pH andhelp dissolve surface coatings like copper oxide. One example of themany different ways in formulating the cleaning solution is combining0.5% HF, 0.1% Citric Acid, and 0.4% NH.sub.4OH by weight mixed indeionized water. The pH level of the solution in this example isapproximately 3. EDTA, oxalic acid, deionized (DI) water or corrosioninhibitors such as benzotriazole may also be used in such cleaningsolutions. It should be noted however, that the present invention is notlimited by formulations of the cleaning solution, and that eachcomponent in the solution may be replaced by different chemical that hassimilar properties.

A method of cleaning a surface of a semiconductor wafer after a chemicalmechanical polishing (CMP) operation includes the steps of applying acleaning or material removal chemical to the surface of thesemiconductor wafer and preferably through a brush that is cast onto abase core. Preferably the porous pad material fills one or more throughholes of the rotatable base and forms an interlocking monolithicstructure with porous pad material on the surface of the base. Even morepreferably the porous pad material fills one or more through holes ofthe rotatable base and forms an interlocking monolithic structure withporous pad material on the inner and the outer surface of the base.Brushes with interlocking porous pad and base structures but withoutthrough channels in the base may have cleaning and material removalchemicals applied to the surface of the substrate by a spray nozzle.Preferably the brush has a porous pad material forming a monolithicinterlocking structure with the base. The semiconductor wafer may havecopper interconnects wherein the cleaning chemical transforming thecopper layer on the surface of the semiconductor wafer into a watersoluble copper oxide layer. Scrubbing the surface of the semiconductorwafer having the cleaning chemical fluid with a brush that has a porouspad material cast onto a base and forms a monolithic interlockingstructure with a base may be used to, but is not limited to, removal offrom between about 100 angstroms and about 150 angstroms of the copperoxide layer from the surface of the semiconductor wafer. The treatedwafer and brush may be further treated by rinsing the semiconductorwafer and the brush with deionized water to remove the water solublecopper oxide from the surface of the semiconductor wafer and the brushprior to cleaning or treating a second semiconductor wafer. The fluidapplication, the scrubbing, and the rinsing steps can be performed in abrush box. The treated substrate will have a copper oxide layer having athickness between about 5 angstroms and about 30 angstroms on thesurface of the semiconductor wafer.

A method of cleaning a surface of a semiconductor wafer after a chemicalmechanical polishing (CMP) operation may further include controlling theamount of the copper oxide layer remaining on the surface of thesemiconductor wafer by controlling an amount of H.sub.2O.sub.2 in thecleaning chemical that flows through the brush cast onto the core.

A brush cast onto a core base such that the porous pad material formingthe brush is interlocked with channels in the base may be used to removean ultra-thin chemical oxide layer, such as SiO.sub.2, from a substrateas part of a post CMP cleaning process. In this process, an acid such ashydrofluoric acid is delivered to the core of the cast on core brushwhere it flows through the porous pad material in the through channelsof the base core to the surface of the brush. Alternatively the acid maybe applied to the surface of the wafer using a sprayer.

Less than 20 angstroms of such oxides may be etched using very dilute HFand brushes interlocked with a rotatable base. Hydrofluoric acid with aconcentration of about 0.005% HF. can be used to perform a controlledremoval of less than approximately 15 angstroms of the oxide. This oxideremoves contaminants, including particles and plated residues, on thesurface of the oxide layer or within the oxide layer, without making thesurface hydrophobic. A thin layer of oxide remains on the surface of theworkpiece so that the surface remains hydrophilic. To clean thickeroxide layers, e.g., greater than approximately 30 angstroms, acontrolled thin oxide etch may be used. For these applications, removalof metallic particle contamination (which may be incorporated into theoxide from the CMP polishing process) is important. The metallicparticle contamination may diffuse into the microelectronic devices onthe workpiece and cause them to fail. Very dilute concentrations of HF(such as 0.005% HF) may be sufficient to remove metallic contamination,depending upon the depth of penetration of the contamination into theoxide layer. For example, if the metallic contamination is more than 20angstroms below the surface, a higher concentration of HF may be needed.The amount of oxide removed is determined by the concentration of HFdelivered to the brush, the dispense flow rate, and time. For removingless than 15 angstroms of a native oxide layer, a 0.005% concentrationof HF may have a slow etch rate, with etch times of 20-60 seconds beingacceptable. The film etch time is important when using higherconcentrations. The concentration of HF can be adjusted to provide anoxide layer removal rate which is consistent with a desired workpiecethroughput or production rate. For back-end CMP processes, removal of upto 100 angstroms of oxide may be required to adequately remove themetallic contamination incorporated therein by the polishing process. Toremove this amount of oxide in less than approximately 40 or 50 seconds,the concentration of HF is increased to 0.5-1.0%.

FIG. 1A illustrates a cross section along the length of a hollowcylindrical tube base 100 with various exemplary through channels 130,150, and 180 for permitting fluid flow between the inner surface 190 ofthe tube with outside surface 120. The through channels may be differentin size as illustrated by 130 and 150. The through holes may include aroughened surface or a non-limiting example of a notch 140 forincreasing adhesion or interlocking of the a porous foam or pad materialused to fill the through channels. An endcap 110 may be optionally usedto close one end of the cylinder during molding and is also useful formounting the finished housing tube to a tool. The endcap 110 will causea source of feed fluid (not shown) to flow through the channels 130,150, and 180. Optional insert 170 may be used to offset the insidediameter of the tube for subsequent insertion of a fluid fitting or astep or series of steps with diameter greater than the inner diameter ofthe base, not shown, may be machined into the base 100 for mating withfluid and machine drive fittings. Endcap 110 and insert 170 may bebonded, molded, or machined into the base 100 and preferably form afluid tight seal. The endcap 110 and inner surface 190 define a volumefor holding a fluid.

FIG. 1B illustrates the hollow cylindrical tube 100 with one or morenon-limiting examples of through channels 130, 150, 180 filled with aporous pad material 152. The porous material 152 is shown just fillingthe through channels so that inner surface 190 and outer surface 120remain substantially free of the porous material 152. In FIG. 1B, theinsert 170 and endcap 110 are shown positioned inside the base. Fluidfitting 114 and machine tool mounting plate 112 are shown prior to beingmounted to the base.

FIG. 1C illustrates the base 100 with through channels 130, 150, and 180filled with a porous material 152. The porous material 152 is shown justfilling the through channels so that inner surface 190 and outer surface120 remain substantially free of the porous material 152. The fluidfitting 114 and machine tool drive mounting plate 112 are shown mountedto the base 100. Fluid fittings permit flow of fluid from a source (notshown) into the core of the base; machine mounting fittings permit therotatable base 100 to be connected to a rotating spindle or fixture forrotating the base in a cleaning or material removal process. Inlet forfluid 106 is provided for by fluid fitting 114. The embodiment shown inFIG. 1C may be covered with a sleeve of a second porous pad material(not shown) cast on the base 100, to form a brush roller. Such a brushroller may be installed in a CMP cleaning tool. In use as a cylindricalbrush, a source of pressurized fluid would be connected to fluid inletfitting 114. Fluid would flow into the device through inlet 160, passthrough inlet 160 and into the core volume defined by endcap 110 and theinner surface 190 of base 100. Fluid would flow out of the exemplaryflow channels 130, 150, and 180 filled with the porous pad material 152and out to the second porous pad layer. The machine tool plate 112 wouldbe connected to a rotating shaft or spindle of the tool to rotate thebrush against the

FIG. 2 is a schematic illustration of a cross section along the lengthof a hollow cylindrical housing base 200 that has a porous pad materialcast onto the base core. Exemplary through channels 230, 250, and 280are filled with a porous material 252 in a mold which also forms a layer256 of the porous pad material on the outer base surface 220. The porouspad material 252 and 256 interlock with the base through holes andoptional surface channels (not shown) to maintain the position andspacing of the protrusions 254 on the pad surface. By interlocking thechannels in base with the porous pad, the movement of the pad by walkingor twisting is reduced or eliminated. The porous pad 252 interlock withthe channels of the base by filling one or more of the channels andpreferably form a monolithic structure with 256 and 254. Preferably thechannels or surface of the base have a shape to mechanically andphysically prevent the porous pad cast or molded into the channels frombeing removed by pulling or twisting of the porous pad during rotation.Optional protrusions 254 are shown covering the porous layer 256.Besides protrusions, the porous layer may have but is not limited torecessed grooves or a flat surface. In the FIG. 2 the porous padmaterials 252, 254, and 256 are preferably all the same material andform a continuous monolithic structure from a molding process. Optionalfluid fitting 214 and machine tool mounting plate 212 are shownconnected to the base 200. Base 200 inner surface 290 remainssubstantially free of the porous material. In use as a cylindricalbrush, a source of pressurized fluid would be connected to fluid inletfitting 214. Fluid would flow into the device through inlet 260, asillustrate by 202, pass through inlet 260 and into the core volumedefined by endcap 210 and the inner surface 290 of base 200. Fluid wouldflow out of the flow channels filled with the porous pad material, forexample illustrated by channel 280, and out to the porous pad layer 256to be deposited on the substrate.

FIG. 3B is a schematic illustration of a cross section along the lengthof a hollow cylindrical housing base 300 with through exemplary channels330,350, and 380 as well as the inner surface 390 and outer surface 320of the base filled or covered with the porous pad material. Throughchannels illustrated by 330, 350, and 380 are filled with a porousmaterial 352 in a mold which also forms layers 356 and 358 of the porouspad material on base surfaces 320 and inner surface 390. The porous padmaterial interlocks with the through channels of the base 300. Optionalprotrusions 354 are shown covering the porous layer 356. Besidesprotrusions, the porous layer may have but is not limited to recessedgrooves or a flat surface. In the FIG. 3B the materials 352, 354, 356,and 358 are preferably all the same and form a continuous monolithicstructure in a molding or casting process. The porous base material 352and 356 that fills at least a portion of the exemplary channels 350 and330 act to prevent lifting of the porous pad material 356 and 354 fromthe base surface during use. It also aids in maintaining the height andthe position of the protrusions or nodes 354 along the base surface orits axis and provides more uniform contact with the substrate surface.Optional fluid fitting 314 and machine tool mounting plate 312 are shownconnected to the base 300 in FIG. 3B; FIG. 3A illustrates an embodimentof FIG. 3B without fluid fitting and machine drive fitting. Porous padmaterial layer 358 inside the base has a thickness measured between padinner surface 362 and base inner base surface 390. Porous pad layer 356has thickness measured between 366 and 364. Protrusions 354 have aheight measured between 368 and 366. The thickness of the porous padlayers 354, 356, and 358 may be varied by changing the shape anddimensions of the mold. In use as a cylindrical brush, a source ofpressurized fluid would be connected to fluid inlet fitting 314. Fluidwould flow into the device through inlet 360 and into the core definedby endcap 310 and the inner surface 390 of base 300. Fluid would flowout of the flow channels such as 330 filled with the porous material andthen distributed out to the porous pad layer 356 and protrusions 354.FIG. 3A does not have fluid or tool fittings 314 and 312 mounted to thebase 300 and plate 310.

FIG. 4 is a schematic diagram illustrating non-limiting through channelsfilled with a porous pad material useful in the practice of theinvention. Base housing 400 is a cylinder with inlet 460 and outlet 482,optionally outlet 482 is covered with an endcap (not shown). The innersurface 490 and outer surface 420 are fluidly connected by throughchannels 450 and 452 and or pores 480, 486 and 484. In FIG. 4 thedifferent sized illustrative pores 480 and 484 are shown filled with theporous pad material while pore 486 is not filled. Through channel 452 isshown not filled and through channel 450 is shown filled with the porouspad material. Preferably the pores and through channels in the base 400are filled with the porous pad material. Also shown is a distribution ofthrough channels and pores along the base 400 to aid in the preferentialdistribution of fluid from the inside of the base to the outer surfaceof the base and into a porous pad material covering the base which isnot shown.

The present invention may also be used as a pad for material removal orcleaning of a substrate. FIG. 5A illustrates a cross section along thediameter of a disk shaped housing base 508 a having sides 506 a and top500 a to form a volume 504 a. A hollow rod 516 a connected to top 500 athrough an optional machine drive or fluid mounting plate which is notshown. Rod 516 a is used to deliver fluid to the pad 556 a and to rotatethe device. Fluid from a pressurized source illustrated by 502 a entersthe device cavity 504 a through the rod 516 a and flows through innerporous pad layer 562 a adhering to the base 508 a with inner surface 590a and an outer surface 520 a. The fluid flows from 504 a throughchannels 550 a, adhering porous pad layer 562 a, and second porous padlayer 556 a, and to porous protrusions 554 a. The first porous padmaterial 562 a adheres to the base surface 520 a and second porous padlayer 556 a and bonds the porous pad material 556 a with the base 508 a.The porous pad layer preferably covers through holes 550 a, but it mayalso fill one or more of the through holes 550 a. Optionally the porouspad material 562 a and 556 a form a single adherent porous pad materialbonded to the base 508 a. Porous pad layer 556 a covers outer surface520 a of base 508 a and may have surface recess features 522 a. Theporous materials 558 a, 562 a are preferably all the same materialcomposition and form a continuous monolithic structure from a molding orcasting process.

The present invention may also be used as a pad for material removal orcleaning of a substrate. FIG. 5B illustrates a cross section along thediameter of a disk shaped housing base 508 b having sides 506 b and top500 b to form a volume 504 b. A hollow rod 516 b connected to top 500 bthrough an optional machine drive or fluid mounting plate which is notshown. Rod 516 b is used to deliver fluid to the pad 556 b and to rotatethe device. Fluid from a pressurized source illustrated by 502 b entersthe device cavity 504 b through the rod 516 b and flows through innerporous pad layer 558 b, into exemplary through channels 550 b, pad layer556 b, and to porous protrusions 554 b. The porous pad material fillingthe through hole 550 b interlocks the pad material with the base 508 b.Porous pad layer has top surface 562 b and covers inner surface 590 b ofthe base 508 b. Porous pad layer 556 b covers outer surface 520 b ofbase 508 b and may have surface recess features 522 b. The porousmaterials 558 b, 552 b, 554 b, and 556 b are preferably all the samematerial composition and form a continuous monolithic structure from amolding process.

Various modifications of the present invention may be made as would beknow to those skilled in the art. For example, FIG. 6 illustrates across section along the diameter of a hollow tube housing base 600 withinner surface 690 and outer surface 620. Through channels 650 are shownfilled with and interlocking a porous pad material which also formsporous pad layer 656 with protrusions 654 covering base outer surface620. The porous material in the channel 650 interlock the porous padmaterial 656 with the base 600. The porous materials in the throughchannels and covering the base form a monolithic structure, porous padmaterial 656 is substantially absent from the inner surface 690 in thecore 672 of the device. The core 672 of the device may be connected arod from the cleaning or material removal tool to accept fluid from thetool and distribute it to the porous pad layer 656 on the surfacethrough channels 650. The base 600 may be connected via a machine drivefitting, not shown, to rotate the base and porous pad material against asubstrate. FIG. 7 shows a cross section along the diameter of a hollowtube housing base 700 with inner surface 790 and outer surface 720.Through channels 750 are shown filled with a porous pad material thatinterlock the base 700 with the pad materials 756 and 758. The porouspad material forms a porous layer 758 covering inner surface 790 of thebase and an outer porous pad layer 756 with protrusions 754 coveringbase outer surface 720. The porous materials in the through channels750, inside the core 772 and covering the base preferably form amonolithic structure. The core 772 of the device accepts fluid through afluid fitting connected to the base 700, not shown, from the tool anddistributes it to the surface porous pad layer 756 through channels 750.The base 700 may be connected via a machine drive fitting, not shown, torotate the base and porous pad material against a substrate to betreated.

FIG. 8A is a schematic diagram of an embodiment of the present inventionhaving a first adherent porous pad material 856 a covering the rotatablesubstrate 820 a having core 872 a. The first porous pad material 856 amay have a second layer of a porous pad material 859 a cast or molded onto at least a portion and preferably all of the first layer of porouspad material 856 a. Base 800 a has through channels 850 a and outersurface 820 a covered with an adherent first porous pad material 856 a.The porous pad material 856 a adhering to the outer surface 820 a may bechemically or mechanically bonded to the rotatable substrate 800 a withsurface 820 a by molding a preformed pad of porous pad material to thebase 800 a. The first porous pad material 856 a covering the base 800 amay be bonded by casting, solvent bonding, or molding the porous pad tothe surface of the rotatable substrate. This first porous pad materialcan serve as an adhesion layer to hold or interlock the second porouspad layers such as 859 a by chemical bonds, or mechanical interlockingbonds, or a combination of these between the first and second padmaterials. The adherent porous pad material 856 a covering the base 800a, preferably covers the through holes 850 a while maintains itsporosity after bonding to the base surface 802 a. This porosity permitsfluid flow from the core 872 a through holes 850 a and to the outer padlayer 859 a as illustrated by 802 a. In optional embodiments the porouspad material may fill a portion of one or more of the through channels850 a, not shown, to form an adherent and interlocking monolithic porouspad material 856 a covering the base surface 802 a. The porous padmaterial layer 856 a covering the outer surface 820 a is preferablythinner than the second porous pad layer 859 a and may or may not haveprotrusions. The outer surface of layer 856 a may be covered with asecond layer of porous pad material 859 a, shown with protrusions, by asecond molding process or by sliding a second preformed porous padmaterial or cleaning brush over the layer 856 a. The second porous padmaterial may be a replaceable sleeve or may have a fluid conductancedifferent from porous material layer 856 a to better distribute fluid toa substrate to be treated by fluid 802 a.

In FIG. 8B a schematic diagram of an embodiment with a an adherentporous layer filling the base through channels is shown. Base 800 b hasthrough channels 850 b filled and outer surface 820 b covered with aninterlocking monolithic porous pad material 856 b. The porous padmaterial layer 856 b covering the outer surface 820 b is thin and doesnot have protrusions. The outer surface of layer 856 b may be coveredwith a second layer of porous pad material 859 b, shown withprotrusions, by a second molding or casting process or by sliding asecond preformed porous pad material or cleaning brush over the layer856 b. The second porous pad material may be a replaceable sleeve or mayhave a fluid conductance different from porous material layer 856 b tobetter distribute fluid to a substrate to be treated by fluid 802 b. Thesecond porous pad material 859 b may have the same or a differentcomposition that first porous pad material 856 b.

The devices of the present invention may be used to remove material fromone or more surfaces of a substrate 910 as illustrated in FIG. 9. Inthis non-limiting diagram, the devices are shown in cross section as abrush roller 920 over the top substrate surface 912 and brush roller 930below the bottom substrate surface 914. The brush 920, similar to thatdetailed in FIG. 7, may receive pressurized fluid 902 from a perforatedrod 992 or fluid fitting attached to the base which is connected to afluid conduit from the cleaning tool (not shown). Fluid 902 flowsthrough the porous pad material layer 958 surrounding the perforated rod992 and through channels 950 filled with the porous pad material. Thefluid is illustratively delivered to the substrate through theprotrusions in the porous pad layer 956 which also removes particles andmaterial from the substrate as it is rotated. Perforated rod 994 or afluid fitting attached to the base delivers fluid 903 to the brush 930which is similar to that depicted in FIG. 7. Fluid 903 flows through theporous pad material layer 958 surrounding the perforated rod 993 andthrough channels 950 filled with the porous pad material. The fluid isillustratively delivered to the substrate through the protrusions in theporous pad layer 956 which also removes particles and or material fromthe bottom of the substrate as it is rotated.

FIG. 10A illustrates a cross section of a second porous brush pad 1059with protrusions and having an inner surface 1080. FIG. 10B illustratesa cross section along the diameter of a hollow tube housing base 1000,with core 1072 and hollow through channels 1050 filled with a porousmaterial 1058 in a monolithic structure. Housing base has inner surface1090 and outer surface 1020. The inner surface 1090 may or may not havea layer of porous pad material. The outer surface 1020 of the base maybe covered with a first porous pad material layer 1058 with outersurface 1062. The first porous pad material may be bonded by casting,solvent bonding, or molding of the porous layer 1058 to the base surface1020 by chemical bonds, mechanical bonds or interlocking, or acombination of these bonds. The inner surface 1080 of second porousbrush pad 1059 in FIG. 10A may be cast, molded, or slid over the outersurface 1062 of first porous pad layer 1058 to form a composite brushdevice 1002 as shown in FIG. 10C. Preferably the second porous brush pad1059 is cast onto the first porous pad layer 1058 and is chemicallybonded, mechanically bonded, or a combination of these bonded to thefirst porous layer. Optionally the porous pad layer 1058 does notinterlock with through channels 1050 (not shown). The first porous padmaterial and the second porous pad material may be a single layer,preferably they are formed from the same material.

FIG. 11A illustrates a cross section of a second porous brush pad 1159with protrusions and having inner surface 1180. FIG. 11B illustrates across section along the diameter of a hollow tube housing base 1100including one or more hollow through channels filled with a porous padmaterial 1152. FIG. 11C illustrates a brush formed by the components inFIG. 11A and FIG. 11B. Device 1102 has porous pad material 1158 fillingand interlocking with channels 1150 to form a monolithic structure withbase 1110. Second porous brush pad 1159 covers the base 1100 andcontacts channels filled with the porous pad material.

One method of retaining the porous pad material on the surface of thehousing base is to form recessed channels, posts, or hollows in thesurface of the surface of the housing. The recessed holes, posts, orchannels preferably have a larger opening at their bottom than attheirtop. In FIG. 12 the base 1200 has exemplary recessed channels 1232and 1234. The upper surface portions 1236 and 1238 are part of the baseouter surface into which the recessed channel 1234 was cut. Porous basematerial 1256 cast onto the base 1200 fills at least a portion of thesurface recess down to the surface 1220 of the base to interlock theporous pad material with the base 1200. This prevents lifting of theporous pad material 1256 from the base surface during use and aids inmaintaining the height and the position of the protrusions or nodes 1254along the base 1200 surface or rotational axis. The base 1200 may alsobe connected to a machine drive fitting, not shown. In use as a brush,the embodiment if FIG. 12 may have chemicals or otherfluids dispensed onthe substrate to be treated by external sprayers as would be know tothose skilled in the art. Channels similar to 1234 and 1232 may beformed in bases having through holes and porous pad material fluidlyconnecting the inner and outer surfaces of the base.

FIG. 13 is a photograph of a cross section of a brush molded onto arotatable base of the present invention. FIG. 13 shows a cross sectionalong the length of a hollow cylindrical housing base 1300 withexemplary through channels 1380 as well as the inner surface 1390 andoutersurface 1320 of the base filled or covered with the porous padmaterial. Through channels illustrated by 1380 are shown filled with aporous material 1352 in a mold which also forms layers 1356 and 1358 ofthe porous pad material on base surfaces 1320 and 1390. The porous padmaterial interlocks with the through channels 1380 of the base 1300.Node protrusions 1354 are shown covering the porous layer 1356. Thematerials 1352, 1354, 1356, and 1358 are all the same and form acontinuous monolithic structure. The porous base material filling theexemplary channels 1352 interlocks 1365 and 1358 and acts to preventlifting of the porous pad material 1356 and 1354 from the base surfaceduring use especially at high rotation rates. Interlocking also aids inmaintaining the height and the position of the protrusions or nodes 1354along the base surface or its axis and provides more uniform contact ofthe nodes 1354 with a substrate surface. Fluid fitting 1314 and cleaningmachine tool endcap 1312 are shown connected to the base 1300. Porouspad material layer 1358 inside the base has a thickness measured betweenpad inner surface 1362 and base inner base surface 1390. The thicknessof the porous pad layers 1354, 1356, and 1358 may be varied by changingthe shape and dimensions of the mold. In use as a cylindrical brush, asource of pressurized fluid would be connected to fluid inlet fitting1314. Fluid would flow into the device through inlet 1360 of a fluidfitting and into the core 1372 defined by the inner surface 1390 of base1300. Fluid would flow through porous pad layer 1358, out of the flowchannels such as 1350 filled with the porous material 1352 and thendistributed out to the porous pad layer 1356 and nodes 1354.

FIG. 14 illustrates a mold which may be used to make a brush molded ontoa rotatable base of the present invention. The mold includes and end cap1401 with o-rings 1406 sealing the endcap 1401 to the mold sleeve 1402.Mold sleeve 1402 is used to create protrusions or recesses in the porouspad and may be surrounded by a shrink wrap film 1403 to retainun-polymerized porous pad monomer and catalyst filling the mold sleeve1402 and in the core assembly 1404 shown with through channels. A topfiller cap 1407 is used to seal the top of the mold sleeve andretainmold core 1405 within the center of the core. Barbed fluid fittings 1408are provided to the top filler cap 1407.

FIG. 15A illustrates an embodiment of the present invention where a castor molded porous pad layer 1520 having optional protrusions 1524 isinterlocked to a rotatable base 1505 through a porous adhesion layer1514. The rotatable base may have a plurality of channels 1510 for theflow of a fluid 1504 from fluid inlet and rotating shaft 1502 coupled tothe base 1506. The fluid 1504 may flow through porous adhesion layer1514, and through the porous pad 1520 having optional protrusions. FIG.15B illustrates an embodiment of the present invention where a cast ormolded porous pad 1558 having optional protrusion 1560 is interlockedwith a nonporous substrate 1550 through a porous adhesion layer 1554.The non porous substrate may be coupled to a rotating vacuum chuck froma cleaning or polishing tool.

FIG. 16 is an illustration of a material removal pad of the presentinvention including a porous pad 1610 with surface protrusions 1612molded. The porous pad 1610 is molded into channels of a rotatable coreand having interchangeable fluid inlet fitting 1620 and tool drivemounting fitting 1600 attached to the core for connection to a rotatableshaft or fixture on a tool for rotating the device.

FIG. 17 is an illustration of the core 1710 of diameter 1730 havinginterchangeable fluid fitting 1720 attached to the core and tool drivemounting fitting 1700 attached to the core for connection to a rotatableshaft or fixture on a tool for rotating the device. The core is shownwith channels 1760 through the core or base 1710. The channels would befilled with the porous pad material from casting to interlock the padmaterial with the base 1710. The length of the channels 1740, theirspacing from each other 1724 and their height 1750 may be varieddepending upon the desired flow rate and distribution of fluid throughthe porous pad material in the channels.

FIG. 18 is an illustration of a cross section of a material removal padof the present invention including a porous pad 1824 molded intochannels, not shown, of a rotatable core 1834 having outside diameter1830. The protrusions 1844 on the porous pad have a diameter 1840 and aheight 1800 from a surface of the pad 1820. The outside diameter of thepad 1810 is measured from the outside of the protrusions 1844.

FIG. 19A is an illustration of an unassembled bare base core 1920including channels 1924 with interchangeable fluid fitting 1910 and tooldrive mounting fitting 1930. The channels 1924 are preferably filledwith a porous pad material to interlock it with the base 1920. FIG. 19Bis an illustration of the fluid fitting and tool mounting fittinginserted into the inside of the coreand having a final assembled lengthof 1940. Although shown with the fittings 1910 and 1930 being insertedinto the inside of the core, similar fittings in this embodiment orother embodiments of the present invention could be adapted by thoseskilled in the art for mounting onto the outer surface of the core. FIG.19C is a Detail A in FIG. 19B and shows the joint formed between thecore 1920 and the fluid fitting 1910. The fluid and machine drivefittings may be attached, mated, or fixed to the core by methodsincluding but not limited to a solvent bond, an ultrasonic weld, radiantheating, or by machined threads on outside surface 1950 of the fittingsand the inside surface 1960 of the core.

FIG. 20 is an illustration of a fluid fitting 1910 of FIG. 19A indetail. The fitting 2010 has a conduit 2040 which extend through thepiece for fluid flow into the core 1920 of FIG. 19 from a materialremoval tool. The inner diameter 2080 may be used for accepting a fluidconduit from the tool. The fitting 2010 may have an o-ring orcompression fitting, not shown, for retaining the fluid conduit with thefitting 2010. The size and configuration of the openings 2060, 2080, and2040 may be varied and is not limited by the present description aswould be known to those skilled in the art of making fluid fittings. Oneadvantage of the present invention is that the porous pad cast onto thecore may be fit with a wide variety of fittings 2010 to adapt the coreto a variety of fluid sources, conduits, and or retaining mechanismsused with any polishing, scrubbing, or cleaning machine.

FIG. 21A is a detailed illustration of the outside of the core 1920 ofthe FIG. 19A. In FIG. 21A the core or base housing 2120 includes anumber of slit or oval shaped channels 2124 through the core that areseparated 2108 from each other along the housing 2120. The slits wouldbe filled with the porous pad material. The width 2116 of the slits mayas well as their separation 2108 may be varied without limitation. FIG.21B is a view of a cross section of the core 2120 whose diameter 2104may be varied depending upon the application and requirements of thetool. The view shows base 2120 inner surface 2154 and outer surface2150, the porous pad material may contact both the outer and innersurfaces. The length 2136 of the slits may also be varied to permitgreater fluid flow through the channels after being filled with a porouspad material. One of the slits at the bottom of the core is shown incross section 2126 and is preferably filled with a porous pad materialin a finished device to interlock the porous pad to the base 2120. Theinside surface of the core may be machined or molded to include one ormore steps or stop for the fluid and tool fittings. The inner diametersof two step 2120 and 2128 are shown for illustrative purposes only. Thedepths 2144 and 2140 of the steps are also shown for illustrativepurposes only.

FIG. 22 is a cross section of core in FIG. 19A illustrating placement ofchannels 2202 and 2204 for interlocking with a porous pad materialthrough the core relative to one another by an angle 2200 which may bevaried. The wall thickness 2110 of the core may be varied depending uponconsiderations such as but not limited to the strength of the corematerial, the desired volume of fluid held by the core, and the fluidpressure drop across the slit. Steps 2120 and 2130 on the inside of thecore may also be varied in their diameter by choice of wall thickness2110 of the core.

FIG. 23 is an illustration of a tool drive mounting fitting 1930 of FIG.19A. The tool mounting fitting 2316 has a keyed opening 2336 with arecess 2320 and optional sidewall taper 2330 defined by and angle whichmates to a rotating element of a tool. The element, not shown, connectsto the fitting 2316 which has been bonded or secured to the core androtates the core and porous pad. The size and configuration of the keyedopening 2336 may be varied and is not limited by the present descriptionas would be known to those skilled in the art of making. One advantageof the present invention is that the porous pad cast onto the core maybe fit with a wide variety of fittings 2316 to adapt the core to anysubstrate coating machine's rotating fixture or spindle or to anypolishing, scrubbing, or cleaning machine's rotating fixture or spindle.

Both the fluid fittings and the tool mounting fittings of the presentinvention may be configured for a zero clearance fitting by matingopposing surfaces with a gasket or o-ring.

FIG. 24 is a view of another example of an unassembled core 2400 forsupporting a porous pad, not shown, that is molded to interlock the padwith channels 2424 through the core. The channels may be filled with aporous pad material for interlocking the pad material with the base2400. The core has an end 2420 into which the reduced end 2410 of theinterchangeable fluid receiving fitting 2414 is inserted and end 2440into which the reduced end 2430 of tool drive mounting fitting 2434 isinserted. The fluid fitting 2414 and machine drive fitting 2434 may beattached, mated, or fixed to the core 2400 by methods including but notlimited to a solvent bond, an ultrasonic weld, radiant bonding, or bymachined threads on outside surface of the fittings and the insidesurface of the core.

FIG. 25 is a detailed illustration the fluid fitting 2414 of FIG. 24.Fluid fitting 2510 has a conduit 2500 which extend through the piece2510 for fluid flow into the core 2400 of FIG. 24 from a source of fluidfrom the material removal tool. The inner diameter 2520 may be used foraccepting a fluid conduit from the tool. The fitting 2510 may also havefor example but not limited to an o-ring or compression fitting, notshown, for retaining the fluid conduit with the fitting 2510. The sizeand configuration of the openings 2500 and 2520 may be varied and is notlimited by the present description as would be known to those skilled inthe art of making fluid fittings. One advantage of the present inventionis that the porous pad cast onto the core 2400 of FIG. 24 may be fitwith a wide variety of fittings 2410 to adapt the core to a fluidsource, conduit, and or retaining mechanism used with any polishing,scrubbing, or cleaning machine. The fluid fitting has a tapered end 2414whose diameter 2524 allows it to be inserted and bonded to the core2400. The size 2534 for the top of the fitting 2510 and the tapered endsize 2550 may be varied with the length and height requirement of anytool to which the assembled device is designed for.

FIG. 26 is a detail illustration of the tool mounting fitting 2434 ofFIG. 24. The tool drive mounting fitting 2600 has one or more keyedopenings 2620 with a recess depth 2634 and opening 2610 with recessdepth 2630 for mating to a rotating element or fixture of a tool. Thekeyed openings may be placed at an angle 2624 around the drive mountfitting 2600 and offset from center 2604. The rotating element of thetool, not shown, connects to the fitting 2600 which has been bonded orsecured to the core and rotates the core and porous pad. The fitting2600 is inserted into to the inside of the core at its end with diameter2638 and secured, by bonding, threaded seal or other sealing technique,to the inside of the base 2400. The reduced diameter portion 2638 of thefitting with length 2640. These dimensions may be varied depending uponthe overall size requirements for the tool and the pad as well as thestrength of the seal required. The size and configuration of the keyedopenings 2620 and 2610 may be varied and is not limited by the presentdescription as would be known to those skilled in the art of making. Oneadvantage of the present invention is that the porous pad cast onto thecore may be fit with a wide variety of fittings 2600 to adapt the coreto any coating, polishing, scrubbing, or cleaning machine's rotatingfixture.

Embodiments of the present invention may be used as a brush in anautomated wafer cleaning station to clean wafer substrates. In someembodiments brushes from a single sized rotatable base can be for usedin a number of different automated wafer cleaning stations to cleanwafer substrates by interchange of fittings on the ends of the base. Thecleaning station may be controlled in an automated way by a cleaningcontroller station. Other substrates such as but not limited to wafers,flat panel displays, optical devices, and hard disks could be cleaned orpolished using similar station with modifications in substrate handlingequipment and chemicals as would be known to those skilled in the artwithout undue experimentation. The wafer cleaning station may include asender station, a cleaning stage, a spin-rinse and dry (SRD) station,and a receiver station. In a cleaning process, semiconductor wafers mayinitially be placed into the sender station. The sender station thendelivers a wafer (one-at-a-time) to the cleaning stage. The cleaningstage may be divided into a first cleaning stage and a second cleaningstage, although having just one cleaning stage will also work. Afterpassing through the cleaning stage, the wafer is passed through an exitspray in order to remove the cleaning fluids and any contaminants. TheSRD station dries the wafer and then it may be delivered to the receiverstation for temporary storage.

A brush mounting system includes a rigid brush core or mandrel on whicha brush is mounted. The mandrel in turn, is mounted between brushmounting assemblies. One brush mounting assembly may be a conventional,motor-driven brush mounting assembly having a cylindrical spindle orother rotating fixture. The brush mounting assembly can be mounted to awall of a wafer scrubbing device via a mounting member such as mountingplate. A bearing may be secured to the mounting plate and the spindle isrotatably mounted on the bearing. The portion of the other mountingassembly which can be connected to the rigid core has rotary motiontransmitted to it by the rigid core and to supply cleaning liquid to thebrush through the mounting assembly that is not motor driven.

Both the sender station and the receiving station are preferably adaptedto receive a cassette containing a number of wafers. The first andsecond cleaning stages preferably include a set of PVA brushes of thepresent invention that are very soft and porous. These brushes aremounted brushes to the tool and are located horizontally from oneanother. The brushes include a base or brush core covered with amonolithic porous pad material that interlocks the porous pad materialwith the core. The brushes may be mounted to first ends of shafts forrotating the brushes. Rotary unions are mounted to second ends of theserotating shafts. The rotating shafts have central cavities formedtherein which allow liquid to flow from the rotary unions through theshafts and into the inside of the brush base. The shafts haveperforations in the regions where the brushes are mounted which allowsliquid to be distributed from shafts to the inner surface of the brushbase or core, through the porous pad material filling the throughchannels of the core and out to the surface of the brush.

A single brush may be used for material removal or cleaning of a singlesubstrate surface. Alternatively, a pair of brushes may be used forscrubbing a top surface and a bottom surface, respectively, of a waferor other substrate. Typically, the wafer is caused to rotate in aparticular direction while the brushes rotate around an axis of rotationwhile the surface of the brushes are in contact with the surfaces of thewafer as illustrated in FIG. 9. The brushes are mounted on brush coresor a base material. The brush cores are configured to have at one end, afluid inlet which connects to tubing or fluid conduit from the tool. Thetubing will thus supply the desired fluids to the core within the brushbase. The brush core with its plurality of holes or channels filled withporous pad material allows the fluids provided into the core touniformly exit the brush core through the porous pad or brush materialtherefore evenly supplying the desired fluid to the brush or padsurface. The base with its plurality of channels filled with the porouspad material interlocks the porous pad material to the base and preventsor reduces walking or twisting of the brush nodes.

Wafers may be scrubbed in a horizontal or a vertical orientation. Thebrushes are configured to rotate in a desired direction such that bothsides of the wafer are evenly scrubbed, using an equal and oppositepressure on each side of the wafer. For more information on verticalwafer scrubbing, reference may be made to U.S. Pat. No. 5,875,507,entitled “Wafer Cleaning Apparatus,” which is hereby incorporatedreference.

The base housing of the present invention may be a cylinder, tube, ormandrel, and alternately may be a disk or shortened cylinder. Thehousing base preferably has an axis of rotational symmetry. FIG. 4 andFIG. 5A illustrate non-limiting alternative embodiments of a rotatablebase or fixture useful in the present invention. Any base shape that canbe covered with a porous pad material, interlock with the porous padmaterial, and make proper contact with a substrate to be cleaned orpolished may be used in the present invention. As shown in FIG. 1, thebase has an inner surface 190 and an outer surface 120. These surfacesare preferably cleaned to remove surface contamination such as oils andionic contaminants prior to molding and coating the base.

A mold may be used to cast a smooth pad surface or a pad surface asshown in FIG. 10B or one with protrusions, the protrusions having avariety of shapes including but not limited to bristles and nodules asillustrated in FIG. 6. The mold may have a coating of perfluorinatedmaterial such as polytetrafluoroethylene applied to its surface to aidin release of the pad from the mold, the mold itself may be made frompolytetrafluoroethylene, or the mold may be made in one or moresegments. A release agent such as paraffin wax in THF may be applied toportions of the surface of the base or the base material may bechemically treated prior to molding. The porous pad material formed inthe mold on the base is removed from the mold.

The inner and outer surfaces of the base may be smooth, knurled, orroughen with a hatch pattern of parallel or intersecting shallow surfacechannels to enhance porous pad material adhesion and interlocking withthe base, and to promote fluid distribution. The surface channels mayhave a various shapes, such as but not limited to notched square orhalve round to interlock the porous pad, and may or may not interconnectthe inner and outer base surfaces. FIG. 12 illustrates a non-limitingexample of surface channels useful for interlocking a porous padmaterial to a substrate where the channels do not interconnect the innerand outer surfaces of the rotatable base. The surface channels retainthe molded porous pad material and prevent it from being pulled orstretched out of the channel and away from the base. Such surfacechannels may include but are not limited to linear channels of variousgeometries along the axis of a tube, spiral channels, or circularsurface channels at different radii across a platen base. It should beunderstood that the actual shape or geometry of the surface channels canbe varied and may be eliminated altogether. The base and surfacechannels may also be provided with a variety of holes, pores, throughchannels or slits fluidly connecting the inner surface of the base withthe outer surface of the base as illustrated in FIG. 4. The base may beany chemically inert polymeric material, including copolymers, materialsuseful in CMP cleaning processes, or CMP material removal processes. Thebase preferably includes chlorinated or halogenated polymers such as butnot limited to CPVC, PVC, PVDF, PFA, and ECTFE. The base material has athickness to make it rigid and maintain its shape during rotation andpressing against a substrate. Additionally the thickness should providesupport to inserted fittings. The wall thickness may be greater thanabout 0.05 inches and preferably ranges from about 0.05 inches togreater than about 0.75 inches, though others may also be useful. In oneembodiment, the holes or through channels are formed closer togethernear the ends of the brush than in the center of the brush. As a result,a greater amount of liquid is provided to the ends of the brush than tothe center. This is a particular advantage in wafer cleaning operationswhere a greater effective wafer surface area near the ends of the brushmust be cleaned.

The porous pad covering the outer surface of the base fills one or moreof the surface channels, pores, holes, through channels, and or slitsand interlocks the porous pad material with the base housing. The porouspad is cast onto the base. This interlocking maintains the alignment ofthe protrusions on the porous pad surface and provides consistentcontact with substrates. By interlocking the channels in base with theporous pad, the movement of the pad by walking or twisting is reduced oreliminated. The porous pad may interlock with the channels of the baseby filling one or more of the channels. Preferably the channels orsurface of the base have a shape to mechanically and physically preventporous pad cast or molded into the channels from being removed bypulling or twisting of the porous pad during rotation. The porous natureof the brush or pad will absorb and evenly distribute the fluidsthroughout the brush or pad. The porous brush or pad can absorb anddistribute fluids to substrates by flow, wicking, or capillary actionthroughout the brush or pad. If desirable through channels may be leftunfilled by the porous pad material during the molding process byfilling them with an insoluble solid or packing them with a plastic plugand then removing the plug after molding.

In a preferred embodiment, the core for a cylindrical base used in aroller or brush may have a outside diameters ranging between about 0.50inch and about 5 inches. For disk shaped bases the diameter may range to12 or more inches. By covering a portion of the inner surface with theporous pad or brush material, the actual volume of the core may bereduced. The layer of porous material covering the inner surface of thebase may be less than about 15 mm.

Endcaps such as but not limited to 214 illustrated in FIGS. 2 and 212also illustrated in FIG. 2 may be connected to the base to provide forconnection of the rotatable base to a cleaning tool, a pressurizedsource of fluid, a fixture for rotating the base from a tool, or acombination of these. As with the base itself, the endcaps may be moldedto the housing, may be machined into a stock piece of base material, ormade separately and bonded to the base. These non-limiting examplesillustrate the variety of way the base housing of the present inventionmay be connected or mated to an existing tool for receiving fluid androtating to perform a material removal function. A variety of fittingsfor connection to a wide variety of tools may be coupled to the base.Endcaps or other fitting may be attached or mated to the core. Suchfittings include but not limited to fluid fittings 1910 and 2414 andmachine drive fittings 1930 and 2434 shown by the non-limiting examplesin FIG. 19A and FIG. 24 respectively. The endcaps may be made separatelyand bonded to the base using chemical, radiant, or ultrasonic bondingtechniques. These non-limiting examples illustrate the variety of waythe base housing of the present invention may be connected or mated toan existing tool for receiving fluid and rotating the base coated with aporous pad material interlocked with the base to perform a materialremoval function. A variety of fittings for connection to a wide varietyof tools may be coupled to the base.

Because the volume within the bore is rapidly filled, the bore will bepressurized rapidly and the fluid will be ready to quickly outflowthrough the plurality of through channels or holes filled with theporous pad material and out to the surface of the porous pad materialcovering the core. The plurality of holes or through channels may have adiameter ranging between about 0.005 inch to about 0.50 inch. A poroussintered tube stock of ceramic or polymeric construction with micronsize holes may also be used as a base. A combination of differentdiameter through holes may be used and distributed across the mandrel orbase. Larger diameter holes or surface area through channels candistribute fluid from the core to the porous pad surface over a widerarea and result in a more even distribution of fluid throughout theentire length of the porous pad covering the brush. Varying the numberof holes or slits in the base may also be used to increase the surfacearea for fluid flow through the base.

The interlocking of the base and the porous pad in a device of thepresent invention can be modified for use in coating a substrate with afluid or for material removal from any number of substrate types, forexample, semiconductor wafers, hard drive discs, flat panel displays,and the like. Additionally, the brush core or brush base can be modifiedin its length or diameter for substrate scrubbing and material removalapplications of any size, for example, 100 mm wafers, 200 mm wafers, 300mm wafers, larger wafers, small hard disks, etc. For 300 mm diameter orlarge wafers the length of the rotatable base may be greater than about25 cm. It should also benoted that any number of fluids can be deliveredthrough the brush or pad, for example, DI water, ammonia containingchemical mixtures, HF containing chemical mixtures, surfactantcontaining chemical mixtures, and many other variations.

The plurality of surface channels or through channels are formed in thebase. The channels can be positioned from a center point of the base toan outer edge of the base in a symmetric or asymmetric pattern fordistributing fluid to the outer surface of the porous pad material. Thechannels may be the same size or different sized across the base.Preferably the channels may be positioned across the base to deliver agreater volume of fluid to the outer edge of the base than to the centerof the base. The fluid within the pores of the pad material may be froma source of pressurized fluid that is in fluid communication with theporous material in the channels of said base through the inner surfaceof said base.

Fluid delivery is accomplished by implementing brush or pad cores thathave a plurality of holes that allow fluids to be fed into the brush orpad core at a particular pressure to be released into an outer brush orpad surface. During use, liquid flows from inside of the base throughone or more perforations or through channels in the base filled with theporous base material. After flowing through the porous base material inthe perforations, the fluid is distributed throughout the porous padmaterial covering the outside the base where it is used with thesubstrate to be treated. Besides fluid inlet pressure, the flow ofliquid from the inner surface of the base to the housing can becontrolled by appropriately selecting the dimensions of the longitudinalslits, holes or pores in the base through which the liquid must flow.Generally, increasing the cross-sectional area increases the flow ofliquid through the particular slit or hole. Thus, the flow of liquidfrom the shaft to the brush or pad housing is readily controlled byselecting the cross-sectional area of the through holes of thedistributor. Variation in the surface area of the perforations orthrough channels in the base may be made along the length or diameter ofthe base. This is illustrated schematically in FIG. 1A where throughchannels 130 and 180 are different size, and this is also illustratedschematically in FIG. 4 where through holes 484 and 480 differ in sizeand also differ from through channels 450. The wall thickness of thebase will also determine the flow of liquid from the inner surface tothe outer surface with a thicker base permitting less flow than athicker base. Lastly, the porosity and surface energy of the porous basematerial contribute to the conductance of fluid. A higher porosity and asurface energy like the fluid are preferable to increase fluid flow andmaintain surface wetting.

As shown in FIG. 12, the device for removing materials, particles, orcontaminants from substrates includes a rotatable base for supporting aporous pad material. The base include an inner surface and an outersurface and a plurality of channels in the base for interlocking theporous pad material with the base. A porous pad material covers at leasta portion of the outer surface of the base and is used for removingmaterial from substrates. The porous pad material fills one or more ofthe channels in the base and interlocks the porous pad material with thebase. As illustrated in FIG. 2 the channels fluidly connect the innersurface with the outer surface of the base. The through channels 250 inthe base distribute fluid from the inner surface of the base to theouter surface of the base through the porous pad material and alsointerlock the porous base material with the base. The through channelsmay be notched, grooved or roughen to aid in retaining or adhering andinterlocking the porous material. Preferably porous pad material alsocovers at least a portion of the outer surface of the base for removingmaterial from substrates. The device in FIG. 16 for removing materials,particles, or contaminants from substrates includes a rotatable base forsupporting a porous pad material. The base include an inner surface andan outer surface and a plurality of channels in the base forinterlocking the porous pad material with the base. A porous padmaterial covers at least a portion of the outer surface of the base andis used for removing material from substrates. The porous pad materialfills one or more of the channels in the base and interlocks the porouspad material with the base. As illustrated in FIG. 21B the channels 2126fluidly connect the inner surface with the outer surface of the base.The through channels 2126 in the base distribute fluid from the innersurface of the base to the outer surface of the base through the porouspad material (not shown). The through channels may be notched, groovedor roughen to aid in retaining or adhering the porous material.Preferably porous pad material also covers at least a portion of theouter surface of the base for removing material from substrates.

The porous pad material may cover a base in the shape of a roller whereat least a portion of the outer surface of a sidewall of a cylinder thatis used to support the porous pad material is covered. Alternatively,the porous pad material may be a base in the shape of a pad or disk asshown in FIG. 5A and FIG. 5B where the porous pad material covers atleast a portion of the outer surface of the endcap of a cylinder and therotatable base is mounted to a single fitting which is used for bothmachine drive and fluid flow to the center of the base.

The porous pad material covers at least a portion of the outer surfaceof the base. The porous pad material may be bonded to one or moresurfaces of the rotatable base to form an adherent layer by chemical,mechanical, or a combination of these bonds. After forming an adherentlayer with the rotatable base housing surface, the porous pad materialpermits fluid flow through the porous pad material. Subsequent layers ofporous pad material may be molded or cast onto the first porous padmaterial bonded to the base. The additional porous pad layer may bechemically, mechanically, or a utilizing a combination of both, bondedto the first porous layer while maintaining porosity to fluid flow fromfluid received from flow channels in the base. Optionally the porous padmaterial may fill one or more of the fluid flow channels in the base.

The porous pad material covers at least a portion of the outer surfaceof the base and the porous pad material fills one or more of the throughchannels in the base. Preferably the porous pad material filling thethrough channels and covering the base surface are continuously formedinto a monolithic structure that interlocks the porous pad material withthe base. More preferably the porous pad material fills the throughchannels or the base and covers both the outer surface and the innersurface of the base in a continuously formed monolithic structure of theporous base material. The porous base material covering the outersurface of the base or housing may have a thickness greater than about 1mm and is preferably from about 1 to about 20 mm.

The devices of the present invention can also include a fluid in theporous pad material which may be pressurized. Fluids may include waterand aqueous chemistries such as but not limited to ammonium hydroxide orhydrofluoric acid. The source of pressurized fluid is in fluidcommunication with the porous material in the channels of device basethrough the inner surface and core of the base.

The porous pad material covering the base preferably includes surfaceprotrusions or recesses for removing particles or materials from asubstrate or for distributing fluid across a substrate. The porous padmaterial with protrusions fills one or more of the channels in the baseand interlocks the porous pad material with the base. The channels inthe base maintain the alignment, height, and or distribution ofprotrusions on the surface of the porous pad material. Preferably thechannels fluidly connect the inner surface with the outer surface of thebase. The through channels in the base distribute fluid from the innersurface of the base to the outer surface of the base through the porouspad material.

The roller and pad devices of the present invention may be made by theacts which include pouring a combination of un-polymerized spongemonomer and a catalyst for polymerizing the monomer into a mold. Themold includes a housing or base with preformed channels that are filledwith the porous pad material to interlock the porous pad material withthe housing. The combination of un-polymerized sponge monomer and acatalyst in the mold are cured and the housing with porous pad materialfilling the channels in the housing released from the mold. The finalproduct is a brush or pad that is cast onto the base. Preferably themold also includes an outer mold for forming a surface texture of theporous pad material covering the housing. The outer mold is used tocontrol the shape, height, and thickness of the outer porous padmaterial. The protrusions may be but are not limited to square shaped orrectangular shaped cylinders. The protrusion or node height may be lessthan about 5 cm, and their diameter less than about 2 cm. Continuoussurface protrusions may also be formed with lengths similar to the brushor pad and widths of about 2 cm or less. More preferably the moldincludes an inner mold for controlling the thickness of the inner layerof the porous pad material coating the inner surface of the housing.

Preferably the porous pad material interlocked with the base includespolyvinylalcohol and the housing includes polyvinylchloride. Preferablythe porous pad material of the present invention includes less than partper million levels of harmful impurities such as metallic ions likecalcium and iron and chloride ions. The porous polymeric pad member issubstantially free from loose portions (e.g., un-cross-linked) of theporous polymeric member greater than about 1 micron in size, or greaterthan about 0.5 micron in size, or greater than about 0.1 micron in size.

As shown in FIG. 3B and FIG. 5B, the devices can range in size andshape, depending upon the application. According to an embodiment, thedevice can be shaped as brush rollers, which have protrusions on theirsurface, or brush rollers that have smooth surfaces. These brush rollershave shapes and sizes to meet the particular cleaning application ormaterial removal from devices such as semiconductor wafers, hard disks,and other substrates. The device can also be in the form disks, puckbrushes, and plugs.

The cast on brushes of the present invention may be made using asuitable material that is film, porous, elastic, and has certainabrasion resistiveness. In most embodiments, the main raw startingmaterial for the device is polyvinyl alcohol, but can be others. Asmerely an example, polyvinyl alcohol is used to form a polyvinyl acetalporous elastic material. The porous material varies in characteristicdepending upon cleanliness, type of pore forming agent or process, typeof aldehyde employed for the conversion of a polyvinyl alcohol to apolyvinyl acetal, and other factors. Preferably the PVA sponge materialmay be prepared from acid catalyst and an aldehyde mixed with a watersolution of polyvinyl alcohol produced from polyvinyl acetatehomopolymer or polyvinyl acetate containing copolymers less than 25% byweight or alloyed with water soluble polymers to no greater than 10% byweight of solids. Other factors which affect the properties of theporous material also include the relative proportions of reactants,reaction temperature and time, and the general condition and startingmaterials in the manufacturing process. Cleanliness of the manufacturingprocess is also important in the manufacture of these devices.

The outer brush or pad surface is made out of a very porous and softmaterial so that direct contact with the delicate surface of a substratedoes not cause scratches or other damage. Preferably, the outer brushsurface is made out of a material that includes polyvinyl alcohol (PVA)foam. Although, other moldable materials such as but not limited tonylon, polyurethane, or a combination of polyurethane and PVA or othercopolymers that interlock with channels in the base and that do notscratch substrate surfaces and provide suitable material removal for theprocess may be used including U.S. Pat. No. 4,083,906 Schindler(polyethylene glycolpolyacrylamide); U.S. Pat. No. 5,311,634 Andros,Nicholas (surfactant air foam systems and core cast); U.S. Pat. No.5,554,659 Rosenblatt, Solomon (Surfactant air foam); U.S. Pat. No.2,609,347 Wilson, Christopher (Early surfactant foam systems); and U.S.Pat. No. 3,663,470 Nishimura et al (Early starch based sponges), thecontents of which are incorporated herein by reference in theirentirety.

Molding a textured brush or pad onto a core eliminates the need forremoving newly cast brushes from a mandrel reducing some losses ofbrushes damaged during this process. Cleaning of sponges on cores to ridthem of excess reagents and fugitive particles is improved during washcycles because they agitate with greater aggression.

Cleaning effectiveness and material removal efficiency of the brushesand pads of the present invention may also depend upon a porosity andpore size of the porous pad material. Porous pad material should provideflexibility to the pad material but not have too much porosity that thepad material looses its strength. The porosity can be more than about85%. In devices where porosity is less than 85% for polyvinyl acetalporous elastic materials, the pad may have poor flexibility. Theporosity may less than about 95%, since a greater porosity value mayprovide poor strength. Other characteristics include a desirable averagepore size or opening. The pore size opening in some embodiments rangesfrom about 10 micron to about 200 microns. In devices where the averagepore opening is less than 10 micron, the porous elastic material mayhave poor elasticity and/or flow properties, thus making the performanceof the cleaning roll unsatisfactory. Alternatively, the average poreopening of more than 200 microns can be unsuitable for a cleaning rollbecause of inconsistent pore configuration. Of course, the selected poresize and porosity depend upon the application and materials used to formthe porous pad material.

The polyvinyl acetal porous elastic material usable for the presentinvention can be produced in a known manner, for example, by dissolvingat least one polyvinyl alcohol having an average degree ofpolymerization of 300 MW to 3,000 MW and a degree of saponification ofnot less than 80% in water to form a 5% to 30% aqueous solution, addinga pore forming agent to the solution, and subjecting the solution toreaction with an aldehyde such as formaldehyde or acetaldehyde until thematerial becomes water-insoluble. In this case the polymer is 50 to 70mole % of acetal units. In some embodiments, where the polymer has lessthan 50 mole % of acetal units, the retained polyvinyl alcohol may oozeout from the product upon use and undesirably contaminate the article tobe cleaned. Where the polymer has more than 70 mole % of acetal units,the device may have poor elasticity and flexibility in otherembodiments.

Although the above devices are generally described in selected shapesand sizes, alternative configurations can also be used. As merely anexample, the polymeric product can have a gear-like configuration, whichhas numerous parallel grooves formed at an angle to the roll.Additionally, protrusions or projections on the surface of the foamproduct can include a variety of shapes, e.g., circular, ellipsoidal,rectangular, diamond, cylindrical pyramidal or the like. Preferably theprotrusion has a square or rectangular shape profile. The spacingbetween adjacent protrusions may be greater than about 1 mm andpreferably range from about 1 mm to about 30 mm or more.

Other techniques can also be used to manufacture porous polymericdevices used for surface treatment applications. These techniquesinclude, among others, an air injected foam or sponge product as well asothers.

Typically, the polishing pad includes brushes that perform themechanical aspect of the CMP process. Brushes can be in the form of apad or in the form of a roller. The roller can also be used to clean thewafer, and commonly includes a plurality of bristles, or protrusionsaround the outer cylindrical surface of the roller. Roller brushes mayhave rectangular protrusions set at a fixed pitch across the entire bodyof the roller. An example of one such roller brush in cross section isshown in FIG. 12. In applications where a square or rectangularprotrusion collects or proliferates contamination (e.g., slurrybuild-up) around the outer edge of the protrusion, which can also causescratches to the underlying substrate, the protrusions are preferablyrounded or spherical in profile.

Various aspect and advantages of the present invention may be understoodby reference to the following non-limiting examples.

Example 1

A quantity of Airvol V-107 was purchased from Air Products Inc. Thepolyvinylalcohol was dissolved as follows: 180 g polyvinylalcohol V-107and 600 grams of tap water. The mixture was mixed and heated to about100.degree. C. until all the polyvinyl alcohol dissolved.

From this mixture, small test batches were made as follows: 175 grams.Polyvinylalcohol solution 30%; 48 grams formaldehyde 37%; 27 gramssulfuric acid 36%; and 13.5 grams corn starch. These ingredients weremixed in the order starch, H.sub.2SO.sub.4, formaldehyde, and last the30% PVA solution. This new mixture was free of entrained air. Thesolution was of low viscosity, opaque, and at room temperature. All ofthis material was poured into a polyvinylchloride mold and heated to70.degree. C. for three hours. Inspection of the sponge formed in themold revealed excess bonding to the PVC mold surface. Some spongematerial was treated with H.sub.2O.sub.2/NaHCO.sub.3 and investigated.

The sponge was well developed, white, soft, and conformed well to themold with good wicking action. PVC surfaces may be pre-treated with amold release agent as 10% solution of paraffin wax in THF.

Example 2

Another part of this invention is a method for preparing a PVC brushmold so that the inventive cleaning brush can be removed efficiently themold without tearing the bristles from the exterior surface of thebrush. It has been found that prior to injecting a PVC brush mold withPVA, that applying a preferred mixture of tetrahydrofuran (THF) andparaffin to the PVC mold creates a coating on which PVA does notappreciably stick. Upon completion of manufacturing, using a PVC moldprepared by the method described, the brush can be easily removed fromthe mold by hand.

Without wishing to be bound by theory, the paraffin and THF mixture,when applied in proper proportions is believed to act upon the PVCmaterial by forming an alloy layer comprised of some or all of theelements PVC, THF, and paraffin. This alloy layer is in the form of avisible sheen which can be physically scratched off of the mold untilthe pure PVC located below the alloy layer, is exposed. The alloy layeris durable and can remain on the mold through a plurality ofmanufacturing cycles. When the alloy layer becomes removed from the PVCmold, it can be re-coated with the paraffin and THF mixture, toregenerate the non-stick qualities of the mold.

A preferred mixture of paraffin and THF which has been found to achievethe proper nonstick coating characteristics is to add about 10 grams ofparaffin to 1 liter of THF (10 g/l). This preferred mixture results ingood fluid characteristics for flowing easily into the mold and readilyachieves the creation of the alloy layer. However, an effective range ofparaffin to THF has been found to be approximately 5 g/l to 20 g/l.Below approximately 5 g/l, the THF volatilizes too quickly for it to acteffectively upon the PVC and create the allow layer, while aboveapproximately 20 g/l the paraffin crystallizes and the mixture is notfluid enough to be useful for coating a PVC brush mold.

As a first step in manufacturing the inventive cleaning brush, a PVCmold is provided. The mold is comprised of a PVC pipe, a core and endcaps for fitting on the PVC pipe. The PVC pipe can be a standardcylindrical PVC pipe with a plurality of properly sized holes, forforming bristles, drilled through the pipe walls. The density of thebristle holes are approximately 70 per square inch, to match the bristledensity of the finished brush. The end caps are provided for fitting oneach end of the pipe, thereby providing a means for preventing theoutflow of PVA material from each end, when the mold is filled. A coreis provided for fitting in a centering position within the hollowcylindrical interior of the PVC pipe, the core for creating the hollowinside diameter of the finished brush. Next, the PVA contacting surfacesof the mold are coated with the paraffin and THF mixture and the alloylayer is allowed to form. When a dry sheen appears on the PV Acontacting surfaces, the alloy layer is formed and the mold is ready tobe used in production. A plastic wrap is next applied around the mold tokeep the PVA from flowing out of the bristle holes. Next, an end cap isplaced on the lower end of the pipe and the mold is filled with the PVAmixture.

The PVA mixture is comprised of formaldehyde or para-formaldehyde, acidcatalyst, PVA, and starch. The starch is a pore former, which createsthe porous quality of the finished brush. Upon filling the mold with thePVA mixture the second end cap is placed on the upper end of the pipe.Next, the mold is vertically spun along its long axis at a sufficientvelocity to allow the PVA mixture to flow into the bristle holes and toforce air bubbles from the PVA. After spinning the upper cap is removed.The forcing of air bubbles from the PVA mixture causes the level of PVAto drop inside of the mold. The mold is next topped-off with anadditional amount of PVA mixture sufficient to fill the mold to anappropriate level for fully forming the inventive brush. The mold can bespun again to get rid of any further minor quantity of air bubbles, ifdesired. Next the mold is placed in an oven to cure overnight, about16-24 hours, at about 125 Fahrenheit. When finally cured, at least oneendcap and the core are removed to access the finished brush. The brushcan then be removed from the pipe by grasping an end of the brush byhand and working it free from the pipe.

Example 3

This prophetic example describes cleaning a wafer having a layer ofcopper metal following a chemical mechanical planarization process. Thewafer may be introduced into a first brush box of the cleaning system.In the first brush box cleaning chemical can be applied to the waferthrough the brushes which are formed of a cast on core porous padmaterial interlocking to the base core of the brush. The cleaningchemical applied through the brushes in the first brush box controllablytransforms copper material on the substrate surface into a water solubleform. The copper material is transformed into a water soluble form inorder to remove a controlled amount of copper from the surface of thewafer. The wafer can be moved from the first brush box to the secondbrush box. In the second brush box a second cleaning chemical may beapplied to the surface of the wafer through the brushes of the secondbrush box in order to clean the wafer surface and clean the brushes ofcopper. The second cleaning chemical may contain the same chemicalcomposition as the cleaning chemical in the first brush box. The purposeof the second cleaning chemical applied through the brushes is to cleanthe brushes of copper and other materials that may have been cleanedfrom the wafer surface. The second cleaning chemical may be appliedthrough the brushes for between about 3 seconds and about 10 seconds.Next the wafer can be rinsed with deionized (DI) water by flowing waterthrough the brushes of the second brush box to remove the secondcleaning chemical from the wafer surface and the brushes. The wafersurface is rinsed preferably for between about 20 seconds and about 40seconds. After the operations in the second brush box, the wafer may betransferred to a spin, rinse, and dry (SRD) station after which thewafer may then be stored in an output station for subsequent processing.

Example 4

In this prophetic example, the brush with cast on a core porous padmaterial interlocking with the brush substrate is used with an etchantto remove a controlled layer of an oxide surface and to maintain ahydrophilic surface.

The CMP process can be performed in a scrubber that scrubs both sides ofa workpiece simultaneously. In the cleaning process hydrofluoric acid(BF) solution can be delivered to the core of a brush having a porousPVA pad layer that interlocks with the brush core. After delivering thehydrofluoric acid (HF) solution to the brush core, the HF solution canbe applied to the workpiece through the channels filled with the porouspad material of the brush. This can be followed by chemical mechanicalscrubbing of the workpiece with the brush. The solution may be appliedconcurrently with the brush scrubbing of the workpiece.

The concentration of the BF solution can be in the range ofapproximately 0.005%-1.0% BF, depending upon the amount of oxide to beremoved. The solution preferably includes a mixture of approximately0.005 percent HF in water. The HF solution can be applied to the waferfor a predetermined amount of time, for example, 20-40, or 25-35 orabout 35 seconds.

Example 5

In this prophetic example, a brush with porous pad material interlockingwith the brush substrate is used in a cleaning step in the manufacturingprocess an integrated circuit such as a microprocessor or a dynamicrandom access memory device.

Methods for making an electronic device such a microprocessor or adynamic random access memory device are well known to those skilled inthe art. These devices include metal interconnect and dielectric layerswhich are applied to active devices on the wafer surface to formelectrical contact with external electronic circuitry and devices. Thesedielectric and metal layers are formed using standard lithography,material deposition, and chemical mechanical planarization techniques.After chemical mechanical planarization, the wafer is cleaned to removeresidual slurry and chemicals by contacting the wafer includingelectronic devices and interconnects with a molded on core PVA brush.This brush has a plurality of channels in the brush base forinterlocking the porous PVA brush pad material with the brush base andfor distributing cleaning fluid to the surface of the wafer with theelectronic devices. Once the wafer has been cleaned it can undergofurther processing steps to complete its fabrication including sealingand dicing the wafer to package the individual integrated circuitdevices.

Example 6

This prophetic example illustrates how a cast on core brush may be madeand bonded to fluid and machine drive fittings. As a first step inmanufacturing the inventive cleaning brush, a PVC mold is provided. Themold is comprised of a PVC pipe, a core and end caps for fitting on thePVC pipe. The PVC pipe can be a standard cylindrical PVC pipe with aplurality of properly sized holes, for forming bristles, drilled throughthe pipe walls. The density of the bristle holes are approximately 70per square inch, to match the bristle density of the finished brush. Theend caps are provided for fitting on each end of the pipe, therebyproviding a means for preventing the outflow of PVA material from eachend, when the mold is filled. A core is provided for fitting in acentering position within the hollow cylindrical interior of the PVCpipe, the core for creating the hollow inside diameter of the finishedbrush. A plastic wrap is next applied around the mold to keep the PVAfrom flowing out of the bristle holes. Next, an end cap is placed on thelower end of the pipe and the mold is filled with the PVA mixture.

The PVA mixture is comprised of formaldehyde or para-formaldehyde, acidcatalyst, PVA, and starch. The starch is a pore former, which createsthe porous quality of the finished brush. Upon filling the mold with thePVA mixture the second end cap is placed on the upper end of the pipe.Next, the mold is vertically spun along its long axis at a sufficientvelocity to allow the PVA mixture to flow into the bristle holes and toforce air bubbles from the PVA. After spinning the upper cap is removed.The forcing of air bubbles from the PVA mixture causes the level of PVAto drop inside of the mold. The mold is next topped-off with anadditional amount of PVA mixture sufficient to fill the mold to anappropriate level for fully forming the inventive brush. The mold can bespun again to get rid of any further minor quantity of air bubbles, ifdesired. Next the mold is placed in an oven to cure overnight, about16-24 hours, at about 125 Fahrenheit. When finally cured, at least oneendcap and the core are removed to access the finished brush. The brushcan then be removed from the pipe by grasping an end of the brush byhand and working it free from the pipe. A fluid fitting as shown in FIG.4 and a machine drive fitting as shown in FIG. 4 made from PVC stockmaterial may be solvent bonded to the PVC core.

Although the present invention has been described with reference tovarious embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, the wafer can be a generallycircular silicon wafer, glass wafer, ceramic wafer, oxide wafer,tungsten wafer although other types of wafers can be used. Further,although various values, materials and dimensions have been provided, itis understood that these values, materials and dimensions are onlyillustrative and not limiting and that other values, materials anddimension can be used. For example, instead of slots having rectangularcross-sections, slots having other cross-sectional shapes such assemicircular slot can be used. Further, although various liquids havebeen set forth, it is understood that substantially any liquid orchemical can be used with a wafer cleaner and brush assembly inaccordance with the present invention. For example, various alcohols,surfactants, ammonia based solutions, buffer solutions, high pHsolutions and low pH solutions can be used. Thus, the invention islimited only by the following claims.

What is claimed is:
 1. A method of cleaning a substrate surfacefollowing chemical mechanical polishing, comprising: engaging a surfaceof a rotating wafer with an outer circumferential surface of a rotatingcylindrical foam roller, the cylindrical foam roller having a pluralityof circumferentially and outwardly extending spaced apart nodulesextending from the outer surface, each nodule defining a heightextending from the outer surface of the cylindrical foam roller to asubstrate engagement surface of the nodule, the substrate engagementsurface of one or more of the nodules having a rounded configuration;and positioning the cylindrical foam roller on the substrate such thatthe one or more nodules are positioned to have only the roundedsubstrate engagement surface contact the substrate such that no linearsurface of the one or more nodules contacts the substrate.
 2. The methodof claim 2, wherein the cylindrical foam roller comprises a hollowrotatable base having one or more through channels that permit fluidflow between an inner surface and an outer surface of the rotatable baseand a porous sponge material including the plurality of nodules thatcovers at least a portion of the outer surface of the hollow rotatablebase and fills one or more of the through channels, thereby interlockingthe porous sponge material and hollow rotatable base such that theheight and alignment of the nodules with respect to the rotatable baseis maintained as the roller is engaged with the substrate, and themethod further comprises injecting a fluid into the inner surface of thehollow rotatable base such that the liquid travels outwardly through thechannels and porous sponge material and onto the substrate.